'use client';

import { useState, useEffect, useCallback } from 'react';
import { useParams } from 'next/navigation';
import { Button } from '@/components/ui/Button';
import { ContractPreview } from '@/components/sales/ContractPreview';
import { getSale, deleteSale, verifyUstId, type SaleResponse } from '@/lib/sales';

export default function SaleDetailPage() {
  const params = useParams();
  const saleId = params.id as string;

  const [sale, setSale] = useState<SaleResponse | null>(null);
  const [loading, setLoading] = useState(true);
  const [error, setError] = useState<string | null>(null);
  const [ustResult, setUstResult] = useState<string | null>(null);

  const fetchSale = useCallback(async () => {
    setLoading(true);
    setError(null);
    try {
      const data = await getSale(saleId);
      setSale(data);
    } catch (err: unknown) {
      const apiErr = err as { error?: { message?: string } };
      setError(apiErr?.error?.message || 'Failed to load sale');
    } finally {
      setLoading(false);
    }
  }, [saleId]);

  useEffect(() => {
    fetchSale();
  }, [fetchSale]);

  const handleDelete = async () => {
    if (!confirm('Verkauf wirklich stornieren?')) return;
    try {
      await deleteSale(saleId);
      fetchSale();
    } catch (err: unknown) {
      const apiErr = err as { error?: { message?: string } };
      setError(apiErr?.error?.message || 'Failed to cancel sale');
    }
  };

  const handleVerifyUstId = async () => {
    try {
      const result = await verifyUstId(saleId);
      setUstResult(`${result.verified ? 'Verifiziert' : 'Nicht verifiziert'}: ${result.message}`);
    } catch (err: unknown) {
      const apiErr = err as { error?: { message?: string } };
      setError(apiErr?.error?.message || 'Failed to verify USt-IdNr.');
    }
  };

  if (loading) return <div data-testid="sale-detail-loading">Wird geladen...</div>;
  if (error) return <div className="bg-red-50 text-red-600 p-3 rounded" data-testid="sale-detail-error">{error}</div>;
  if (!sale) return <div data-testid="sale-detail-not-found">Verkauf nicht gefunden</div>;

  return (
    <div className="space-y-6" data-testid="sale-detail">
      <div className="flex items-center justify-between">
        <h1 className="text-2xl font-bold">Verkauf #{sale.id.slice(0, 8)}</h1>
        <div className="flex gap-2">
          <Button onClick={handleVerifyUstId} data-testid="sale-verify-ust-btn">
            USt-IdNr. prüfen
          </Button>
          <Button onClick={handleDelete} variant="secondary" data-testid="sale-delete-btn">
            Stornieren
          </Button>
        </div>
      </div>

      {ustResult && (
        <div className="bg-blue-50 text-blue-600 p-3 rounded" data-testid="sale-ust-result">
          {ustResult}
        </div>
      )}

      <div className="grid grid-cols-2 gap-4">
        <div className="bg-gray-50 p-4 rounded">
          <h2 className="font-semibold mb-2">Fahrzeug</h2>
          {sale.vehicle ? (
            <div data-testid="sale-detail-vehicle">
              <p>{sale.vehicle.make} {sale.vehicle.model}</p>
              <p className="text-sm text-gray-600">FIN: {sale.vehicle.fin}</p>
              <p className="text-sm text-gray-600">Typ: {sale.vehicle.vehicle_type}</p>
            </div>
          ) : (
            <p className="text-gray-500">Nicht verfügbar</p>
          )}
        </div>

        <div className="bg-gray-50 p-4 rounded">
          <h2 className="font-semibold mb-2">Käufer</h2>
          {sale.buyer ? (
            <div data-testid="sale-detail-buyer">
              <p>{sale.buyer.company_name}</p>
              <p className="text-sm text-gray-600">{sale.buyer.address_city}, {sale.buyer.address_country}</p>
              {sale.buyer.vat_id && <p className="text-sm text-gray-600">USt-IdNr.: {sale.buyer.vat_id}</p>}
            </div>
          ) : (
            <p className="text-gray-500">Nicht verfügbar</p>
          )}
        </div>
      </div>

      <div className="bg-gray-50 p-4 rounded">
        <h2 className="font-semibold mb-2">Verkaufsdetails</h2>
        <div className="grid grid-cols-3 gap-4">
          <div>
            <span className="text-sm text-gray-500">Preis</span>
            <p className="font-medium" data-testid="sale-detail-price">
              {new Intl.NumberFormat('de-DE', { style: 'currency', currency: 'EUR' }).format(sale.sale_price)}
            </p>
          </div>
          <div>
            <span className="text-sm text-gray-500">Datum</span>
            <p className="font-medium">{new Date(sale.sale_date).toLocaleDateString('de-DE')}</p>
          </div>
          <div>
            <span className="text-sm text-gray-500">Status</span>
            <p className="font-medium">{sale.status}</p>
          </div>
          <div>
            <span className="text-sm text-gray-500">GwG</span>
            <p className="font-medium">{sale.is_gwg ? 'Ja' : 'Nein'}</p>
          </div>
        </div>
      </div>

      <ContractPreview saleId={sale.id} contractPdfPath={sale.contract_pdf_path} />
    </div>
  );
}